SARS-CoV-2 Virus Found Throughout Retinal Layers

Among patients with COVID-19, presumed viral particles from SARS-CoV-2 can be found in various layers of the retina and may also be linked with the infection’s ocular manifestations, according to findings published in JAMA Ophthalmology.

Through the use of real-time polymerase chain reaction and immunological methods for protein detection, investigators suggest that deceased patients with COVID-19 may present with SARS-CoV-2 viral particles in the retina. A team of investigators from Brazil and Canada conducted an analysis in which they aimed to display the presence of presumed SARS-CoV-2 viral particles and the associated proteins in the eye in patients with COVID-19. The main outcome was the presence of presumed SARS-CoV-2 viral particles confirmed by immunofluorescence and transmission electron microscopy.

A total of 3 eyes from 3 deceased patients were evaluated. All 3 patients (2 men, 1 woman) were treated in intensive care units, required mechanical ventilation, and developed severe pulmonary involvement from COVID-19. Their ages at death ranged from 69 years to 78 years. More than 50% of the patients’ lungs had multifocal pulmonary ground-glass opacities noted via chest tomography imaging. They were all treated with heparin, antibiotics, and corticosteroids.

Presumed SARS-CoV-2 viral particles were located near the nuclei of retinal cells and appeared as small vesicles that had an average diameter of 70 nm. The particles were associated with a complex membrane network, the viral factory, that involves the endoplasmic reticulum-Golgi complex. Both major proteins of the virus, the spike protein (S) and the nucleocapsid (N) protein were found in the ganglion cell layer, inner plexiform layer, inner nuclear layer, outer plexiform layer, and outer nuclear layer of the retina. The S and N proteins were also found in the pigment epithelium and choroid.

“Given that these findings support the presence of viruses that presumably are SARS-CoV-2 in the retina, research should assess whether retinal changes are related only to secondary microvascular and immunological changes, coincidence to a very prevalent infection or the virus’ direct presence, or a combination of these,” according to the researchers. “The findings may help to elucidate the virus’ pathophysiological mechanisms, which may allow a better understanding of the sequelae of the disease and may direct some avenues of future research.”

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